Offset machines are known in the art and therefore will only be briefly explained. A web or a sheet to be printed is passed between printing rollers or transfer rollers. The web or the sheets are made to abut on a blanket cylinder for application of the print to be applied in the individual printing unit in the offset machine. The blanket cylinder is in contact with a plate cylinder which transfers the colour print which is to be placed on the web. The plate cylinder is in contact with dampening unit and an inking unit applying damp and ink, respectively. Thus, an offset plate on the plate cylinder will be rotated whereby water receptive parts are dampened by the rollers of the dampening unit. Then the ink receptive parts of the offset plate are provided with ink from the inking rollers in the inking unit. The formed image is then applied to the blanket cylinder which in turn applies the ink onto the web or the sheet. Preferably a paper web is used, but other materials may also be used for printing.
A printing unit according to the present invention may be used in a traditional offset machine, for example of the type disclosed in EP 767.058. The contents of this patent application is hereby incorporated by reference, as the printing unit may form a part of an offset machine constructed according to the same principle and with the same sheet feeder and sheet delivery means at the beginning and the end of the printing unit, just like there may be used similar means for transferring paper web or sheets between different, consecutive printing units to apply the finished image to the web. Likewise, the same type of printing ink may be employed. Offset machines may be equipped with a lacquering unit. The lacquering unit will typically be constructed with a plate cylinder onto which the lacquer is applied from a roller arrangement which is supplied from a pan with clear lacquer.